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• how to get tables of an access db into a list box using c#?

  - by fathatsme

  hi evry1! i needed to create a form in which i hav to browse and open mdb files --- i did this part usin oprnfile dialogue! private void button1_Click(object sender, EventArgs e) { OpenFileDialog oDlg = new OpenFileDialog(); oDlg.Title = "Select MDB"; oDlg.Filter = "MDB (*.Mdb)|*.mdb"; oDlg.RestoreDirectory = true; string dir = Environment.GetFolderPath(Environment.SpecialFolder.Desktop); oDlg.InitialDirectory = dir; DialogResult result = oDlg.ShowDialog(); if (result == DialogResult.OK) { textBox1.Text = oDlg.FileName.ToString(); } } **this is my code so far!!! now i need to make 3 list boxes!! 1st one to display the table names of the db! 2nd to to display field names when clicked on table name!!! 3rd to display attributes on fiels on clickin on it! v can edit the attribute values and on clickin of save button it should update the database!!! pls help** i'm new to C# so if u could pls help specifically on d doubt i asked it wud b really helpful to me

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• Using overloaded operator== in a generic function

  - by Dimitri C.

  Consider the following code: class CustomClass { public CustomClass(string value) { m_value = value; } public static bool operator==(CustomClass a, CustomClass b) { return a.m_value == b.m_value; } public static bool operator!=(CustomClass a, CustomClass b) { return a.m_value != b.m_value; } public override bool Equals(object o) { return m_value == (o as CustomClass).m_value; } public override int GetHashCode() { return 0; /* not needed */ } string m_value; } class G { public static bool enericFunction1<T>(T a1, T a2) where T : class { return a1.Equals(a2); } public static bool enericFunction2<T>(T a1, T a2) where T : class { return a1==a2; } } Now when I call both generic functions, one succeeds and one fails: var a = new CustomClass("same value"); var b = new CustomClass("same value"); Debug.Assert(G.enericFunction1(a, b)); // Succeeds Debug.Assert(G.enericFunction2(a, b)); // Fails Apparently, G.enericFunction2 executes the default operator== implementation instead of my override. Can anybody explain why this happens?

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• How do virtual destructors work?

  - by Jack

  I am using gcc. I am aware how the virtual destructors solve the problem when we destroy a derived class object pointed by a base class pointer. I want to know how do they work? class A { public: A(){cout<<"A constructor"<<endl;} ~A(){cout<<"A destructor"<<endl;} }; class B:public A { public: B(){cout<<"B constructor"<<endl;} ~B(){cout<<"B destructor"<<endl;} }; int main() { A * a = new B(); delete a; getch(); return 0; } When I change A's destructor to a virtual function, the problem is solved. What is the inner working for this. Why do I make A's destructor virtual.

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• Perl Linux::Inotify2 - can't respond to events anymore

  - by alcy

  I am getting some really weird behavior when using Linux::Inotify2 module for watching a directory for any newly created files. I had made a test script to see how it worked, and once that was done, I went on to incorporating its usage in the other scripts, in which it didn't work. Then, when I tried my earlier test script again to find some information, strangely that stopped working as well. It hasn't worked since then. There were no package/distro upgrades during that time. The problem is that it has stopped responding to events. Here's the test script: #!/usr/bin/perl use strict; use warnings; use Linux::Inotify2; my $inotify = new Linux::Inotify2 or die "unable to create new inotify object: $!"; my $dir = "/my/dir"; $inotify->watch($dir, IN_CREATE, sub { my $e = shift; print $e->fullname; }) or die " Can't watch $!"; 1 while $inotify->poll; A strace on the running script kills the script. Otherwise when strace is used when starting the script, then it does seem to read the new events, but there's no response to those events. Any suggestions for debugging this further ?

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• How to use JOIN using Hibernate's session.createSQLQuery()

  - by javauser71

  Hi All, I have two Entity (tables) - Employee & Project. An Employee can have multiple Projects. Project table's CREATOR_ID field refers to Employee table's ID field. Employee entity maintains a list of Project. Using EntityManager following query works fine - "entityManager.createQuery("select e from EmployeeDTO e, ProjectDTO p where p.id = ?1 and p.creator.id=e.id"); But since I have the LAZY association relationship, I get error: "Could not initialize proxy - no Session" if I try to access Project info from Employee entity. This is expected and so I am using Hibernate's Session to create query as shown below. Session session = HibernateUtil.getSessionFactory().openSession(); org.hibernate.Query q = session.createSQLQuery("SELECT E FROM EMPLOYEE_TAB E, PROJECT_TAB P WHERE P.ID = " + projectId + " AND P.CREATOR_ID = E.ID") .addEntity("EmployeeDTO ", EmployeeDTO.class) .addEntity("ProjectDTO", ProjectDTO.class); But I get error like: "Column 'E' is either not in any table in the FROM list or appears within a join specification and is outside the scope of the join specification..." Can anyone suggest what will be the right JOIN syntax for such case? If I use ("SELECT * FROM EMPLOYEE_TAB E, ........") - it gives other error: "java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to com.im.server.dto.EmployeeDTO". Thanks in advance.

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• form_form and custom parameter in path_prefix

  - by fguillen

  Hi people, I have this route: # config/routes.rb map.namespace :backshop, :path_prefix => '/:shop_id/admin' do |backshop| backshop.resources :items end And I want to use the form_for magic to reuse the same form on both: new and edit views: <% form_for [:backshop, @item] do |f| %> This used to works, and used to build a create url for the item or update url for the item depending on the status of the @item object. But this is not working on this case because the routes don't exists without the shop_id parameter, and I don't know how to say to the form_for something like this: <% form_for [:backshop, @item], :shop_id => @shop do |f| %> Because it tries to use the @item like the :shop_id parameter. Or like this <% form_for [:backshop, @shop, @item] do |f| %> Because it tries to build this url: backshop_shop_order_path I Know I can just to extract the form_for declaration from the partial and do different calls on depending if new or edit: <% form_for( @item, :url => backshop_items_path( @shop ) ) do |f| %> and <% form_for( @item, :url => backshop_item_path( @shop, @item ) ) do |f| %> But I just wanted don't do this because I have a bunch of models and is a few boring :) Thanks for any suggestion f.

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• How do I code a tree of objects in Haskell with pointers to parent and children?

  - by axilmar

  I've got the following problem: I have a tree of objects of different classes where an action in the child class invalidates the parent. In imperative languages, it is trivial to do. For example, in Java: public class A { private List<B> m_children = new LinkedList<B>(); private boolean m_valid = true; public void invalidate() { m_valid = false; } public void addChild(B child) { m_children.add(child); child.m_parent = this; } } public class B { public A m_parent = null; private int m_data = 0; public void setData(int data) { m_data = 0; m_parent.invalidate(); } } public class Main { public static void main(String[] args) { A a = new A(); B b = new B(); b.setData(0); //invalidates A } } How do I do the above in Haskell? I cannot wrap my mind around this, since once I construct an object in Haskell, it cannot be changed. I would be much obliged if the relevant Haskell code is posted.

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• How to store arbitrary data for some HTML tags

  - by nickf

  I'm making a page which has some interaction provided by javascript. Just as an example: links which send an AJAX request to get the content of articles and then display that data in a div. Obviously in this example, I need each link to store an extra bit of information: the id of the article. The way I've been handling it in case was to put that information in the href link this: <a class="article" href="#5"> I then use jQuery to find the a.article elements and attach the appropriate event handler. (don't get too hung up on the usability or semantics here, it's just an example) Anyway, this method works, but it smells a bit, and isn't extensible at all (what happens if the click function has more than one parameter? what if some of those parameters are optional?) The immediately obvious answer was to use attributes on the element. I mean, that's what they're for, right? (Kind of). <a articleid="5" href="link/for/non-js-users.html"> In my recent question I asked if this method was valid, and it turns out that short of defining my own DTD (I don't), then no, it's not valid or reliable. A common response was to put the data into the class attribute (though that might have been because of my poorly-chosen example), but to me, this smells even more. Yes it's technically valid, but it's not a great solution. Another method I'd used in the past was to actually generate some JS and insert it into the page in a <script> tag, creating a struct which would associate with the object. var myData = { link0 : { articleId : 5, target : '#showMessage' // etc... }, link1 : { articleId : 13 } }; <a href="..." id="link0"> But this can be a real pain in butt to maintain and is generally just very messy. So, to get to the question, how do you store arbitrary pieces of information for HTML tags?

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• Dont understand the concept of extends in URL.openConnection() in JAVA

  - by user1722361

  Hi I am trying to learn JAVA deeply and so I am digging into the JDK source code in the following lines: URL url = new URL("http://www.google.com"); URLConnection tmpConn = url.openConnection(); I attached the source code and set the breakpoint at the second line and stepped into the code. I can see the code flow is: URL.openConnection() - sun.net.www.protocol.http.Handler.openConnection() I have two questions about this First In URL.openConnection() the code is: public URLConnection openConnection() throws java.io.IOException { return handler.openConnection(this); } handler is an object of URLStreamHandler, define as blow transient URLStreamHandler handler; But URLStreamHandler is a abstract class and method openConnection() is not implement in it so when handler calls this method, it should go to find a subclass who implement this method, right? But there are a lot classes who implement this methods in sun.net.www.protocol (like http.Hanlder, ftp.Handler ) How should the code know which "openConnection" method it should call? In this example, this handler.openConnection() will go into http.Handler and it is correct. (if I set the url as ftp://www.google.com, it will go into ftp.Handler) I cannot understand the mechanism. second. I have attached the source code so I can step into the JDK and see the variables but for many classes like sun.net.www.protocol.http.Handler, there are not source code in src.zip. I googled this class and there is source code online I can get but why they did not put it (and many other classes) in the src.zip? Where can I find a comprehensive version of source code? Thanks!

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• Calling child constructor by casting (ChildClass)parentObject; to track revisions

  - by FreshCode

  To track revisions of a Page class, I have a PageRevision class which inherits from Page and adds a revision ID (Guid RevisionID;). If possible, how should I cast an existing Page object to a PageRevision and ensure that the PageRevision constructor is called to create a new revision ID? I could could have a PageRevision(Page page) constructor which generates the Guid and copies all the Page attributes, but I want to automate it, especially if a Page class has many attributes (and I later add one, and forget to modify the copy constructor). Desired use Page page = new Page(123, "Page Title", "Page Body"); // where 123 is page ID PageRevision revision = (PageRevision)page; // now revision.RevisionID should be a new Guid. Page, PageRevision classes: public class Page { public int ID { get; set; } public string Title { get; set; } public string Body { get; set; } } public class PageRevision : Page { public Guid RevisionID { get; set; } public PageRevision() { this.RevisionID = Guid.NewGuid(); } }

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• nothrow or exception ?

  - by Muggen

  I am a student and I have small knowledge on C++, which I try to expand. This is more of a philosophical question.. I am not trying to implement something. Since #include <new> //... T * t = new (std::nothrow) T(); if(t) { //... } //... Will hide the Exception, and since dealing with Exceptions is heavier compared to a simple if(t), why isn't the normal new T() not considered less good practice, considering we will have to use try-catch() to check if a simple allocation succeeded (and if we don't, just watch the program die)?? What are the benefits (if any) of the normal new allocation compared to using a nothrow new? Exception's overhead in that case is insignificant ? Also, Assume that an allocation fails (eg. no memory exists in the system). Is there anything the program can do in that situation, or just fail gracefully. There is no way to find free memory on the heap, when all is reserved, is there? Incase an allocation fails, and an std::bad_alloc is thrown, how can we assume that since there is not enough memory to allocate an object (Eg. a new int), there will be enough memory to store an exception ?? Thanks for your time. I hope the question is in line with the rules.

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• Is the below thread pool implementation correct(C#3.0)

  - by Newbie

  Hi Experts, For the first time ever I have implemented thread pooling and I found it to be working. But I am not very sure about the way I have done is the appropriate way it is supposed to be. Would you people mind in spending some valuable time to check and let me know if my approach is correct or not? If you people find that the approach is incorrect , could you please help me out in writing the correct version. I have basicaly read How to use thread pool and based on what ever I have understood I have developed the below program as per my need public class Calculation { #region Private variable declaration ManualResetEvent[] factorManualResetEvent = null; #endregion public void Compute() { factorManualResetEvent = new ManualResetEvent[2]; for (int i = 0; i < 2; i++){ factorManualResetEvent[i] = new ManualResetEvent(false); ThreadPool.QueueUserWorkItem(ThreadPoolCallback, i);} //Wait for all the threads to complete WaitHandle.WaitAll(factorManualResetEvent); //Proceed with the next task(s) NEXT_TASK_TO_BE_EXECUTED(); } #region Private Methods // Wrapper method for use with thread pool. public void ThreadPoolCallback(Object threadContext) { int threadIndex = (int)threadContext; Method1(); Method2(); factorManualResetEvent[threadIndex].Set(); } private void Method1 () { //Code of method 1} private void Method2 () { //Code of method 2 } #endregion }

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• Some questions about focus on WPF

  - by ThitoO

  Hello, I've a little problem about focus on WPF. I whant to create a window, always on top, and that never get the focus (even if we click on it). Here's my solution : public partial class SkinWindow : Window { public SkinWindow() { InitializeComponent(); Loaded += ( object sender, RoutedEventArgs e ) => SetNoActiveWindow(); } private void SetNoActiveWindow() { WindowInteropHelper helper = new WindowInteropHelper( this ); SetWindowLong( helper.Handle, GWL_EXSTYLE, WS_EX_NOACTIVATE ); LockSetForegroundWindow( LSFW_LOCK ); } const int GWL_EXSTYLE = -20; const int WS_EX_NOACTIVATE = 134217728; const int LSFW_LOCK = 1; [DllImport( "user32" )] public static extern bool LockSetForegroundWindow( uint UINT ); [DllImport( "user32" )] public static extern IntPtr SetWindowLong( IntPtr hWnd, int nIndex, int dwNewLong ); } First problem : It's works, but I've to select an other window to "remove" the focus of my application (after the focus is not gave again, even if I click on my window). Second problem : When I move or resize the window, the modifications happens when I drop the window. Do you have any ideas / links / docs ? Thank you :)

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• 3D coordinate of 2D point given camera and view plane

  - by Myx

  I wish to generate rays from the camera through the viewing plane. In order to do this, I need my camera position ("eye"), the up, right, and towards vectors (where towards is the vector from the camera in the direction of the object that the camera is looking at) and P, the point on the viewing plane. Once I have these, the ray that's generated is: ray = camera_eye + t*(P-camera_eye); where t is the distance along the ray (assume t = 1 for now). My question is, how do I obtain the 3D coordinates of point P given that it is located at position (i,j) on the viewing plane? Assume that the upper left and lower right corners of the viewing plane are given. NOTE: The viewing plane is not actually a plane in the sense that it doesn't extend infinitely in all directions. Rather, one may think of this plane as a widthxheight image. In the x direction, the range is 0--width and in the y direction the range is 0--height. I wish to find the 3D coordinate of the (i,j)th element, 0

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• Nullable values in C++

  - by DanDan

  I'm creating a database access layer in native C++, and I'm looking at ways to support NULL values. Here is what I have so far: class CNullValue { public: static CNullValue Null() { static CNullValue nv; return nv; } }; template<class T> class CNullableT { public: CNullableT(CNullValue &v) : m_Value(T()), m_IsNull(true) { } CNullableT(T value) : m_Value(value), m_IsNull(false) { } bool IsNull() { return m_IsNull; } T GetValue() { return m_Value; } private: T m_Value; bool m_IsNull; }; This is how I'll have to define functions: void StoredProc(int i, CNullableT<int> j) { ...connect to database ...if j.IsNull pass null to database etc } And I call it like this: sp.StoredProc(1, 2); or sp.StoredProc(3, CNullValue::Null()); I was just wondering if there was a better way than this. In particular I don't like the singleton-like object of CNullValue with the statics. I'd prefer to just do sp.StoredProc(3, CNullValue); or something similar. How do others solve this problem?

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• A loop (while/foreach) with "offset" wrapping and

  - by DarkGhostHunter

  After applying what wrapping objects using math operator, I just tought it will be over. But no. By far. <?php $faces= array( 1 => '<div class="block">happy</div>', 2 => '<div class="block">sad</div>', (sic) 21 => '<div class="block">angry</div>' ); $i = 1; foreach ($faces as $face) { echo $face; if ($i == 3) echo '<div class="block">This is and ad</div>'; if ($i % 3 == 0) { echo "<br />"; // or some other wrapping thing } $i++; } ?> In the code I have to put and ad after the second one, becoming by that the third object. And then wrap the three all in a <div class="row"> (a br after won't work out by design reasons). I thought I will going back to applying a switch, but if somebody put more elements in the array that the switch can properly wrap, the last two remaining elements are wrapped openly. Can i add the "ad" to the array in the third position? That would make things simplier, only leaving me with guessing how to wrap the first and the third, the fourth and the sixth, an so on.

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• Getting a Script Error Every Time I Click a Link

  - by Flip4Life

  I have everything working perfectly on my site, but for some reason, I get an error message in console whenever I click a link anywhere on my site. The error has to do with this line of coding here: jQuery(function($){ $('.navbar a, .scroll a, .smoothscroll a').bind('click',function(event){ var $anchor = $(this); $('html, body').stop().animate({ scrollTop: $($anchor.attr('href')).offset().top }, 850,'easeInOutExpo'); event.preventDefault(); }); }); And the error I am getting is this: "SCRIPT5007: Unable to get value of the property 'top': object is null or undefined custom.min.js, line 6 character 197" The exact code it is highlighting is this part of the above code: $('html, body').stop().animate({ scrollTop: $($anchor.attr('href')).offset().top }, 850,'easeInOutExpo') All I know is that when I remove the above code, my scroll-to links stop working on pages such as these: http://www.northtownsremodeling.com/things-to-know.php You can see the popup error happen and stay in the console easily by going to a page with a filter like this: http://www.northtownsremodeling.com/bathroom/ And clicking one of the filter buttons. Ultimately, I am trying to make it so my scroll-to setting still works, but not have that error come up anymore. I made this script a long time ago, and I'm really confused as to what could be causing this error when everything is functioning perfectly otherwise? Thanks!

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• Which approach is better in term of saving the data? How to handle this?

  - by dewacorp.alliances

  Hi there I have Telerik grid within a Telerik grid. Due to I have a different view between insert and edit mode, so as per suggested I have to use UserControl instead. Inside this control, it could have another Telerik grid plus bunch of ASP.NET textboxes. This thing works well. My dilemma is this: Scenario 1: Handling the save in the user control - OnClick event I have a button to save this. I need to get the value of the "selected grid" so I am using this snippet below and again works well. foreach (GridDataItem dataItem in radgrdTariffNetworkDistributorRateItems.SelectedItems) { string ID = dataItem.OwnerTableView.DataKeyValues[dataItem.ItemIndex]["SupplierRateItemID"].ToString(); } But then how do I get the id of the parent grid where this control sit? I use the following this event to save: protected void bttnNetworkTariffReviewItemInsert_Click(object sender, EventArgs e) the e of course not the right one though?!?!? GridDataItem parentItem = (GridDataItem)e.Item.OwnerTableView.ParentItem; string reviewID = parentItem.OwnerTableView.DataKeyValues[parentItem.ItemIndex]["ID"].ToString(); Scenario 2: Handling the save in the page instead (OnInsertCommand on the master grid) With this approach works well to get id of the grid etc BUT I am having a problem to get selected grid in the UserControl and plus couple controls value. How do I make this feasible? Logically, I should handle this at the user control level to save but again because the user control relying on the child grid I am having trouble to get this value. I am appreciated your suggestion.

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• Return node level of hierarchical xml

  - by Ryan

  In a treeview you can retrieve the level of an item. I am trying to accomplish the same thing with the given input being an object. The XML data I will use for this example would be something like the following <?xml version="1.0" encoding="utf-8" ?> <Testing> <Numbers> <Number val="1"> <Number val="1.1"> <Number val="1.1.1"> <Number val="1.1.2" /> <Number val="1.1.3" /> <Number val="1.1.4" /> </Number> </Number> <Number val="1.2" /> <Number val="1.3" /> <Number val="1.4" /> </Number> <Number val="2" /> <Number val="3" /> <Number val="4" /> </Numbers> <Numbers> <Number val="5" /> <Number val="6" /> <Number val="7" /> <Number val="8" /> </Numbers> </Testing> This one is kicking my butt!

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• Using Visual Studio to make non aspx code-behind pages

  - by rizzle

  I want to build my own "code behind" like pages so that i can have HTML in a HTML file and code in cs file but be able to have Intellesense for the tokens in the HTML file. (i know that's what the .NET page class does, but i want to have something much lighter) EG: in the .html file: <%@ Directive classname="HTMLSnippet" %> <html> <body> <div>[%message%] </body> </html> and in a .cs file public class MyClass : HTMLSnippet { public class MyClass () { snippet.message = "message goes here" } } So my question is how do make the HTMLSnippet class so that it's members are automatically created, and specifically show up in Intellesense as i add tokens to the .html file? I know that .net currently does it by creating the designer.cs file and basically builds a class with all the elements from the page as it goes, and that would work fine but how can i get visual studio to generate that before compiling so that it shows up in Intellesense. Thanks! Clarification I'm not using this as a handler yet, i want to use this to have HTML snippets with tokens be usable in code as an object with properties. so almost like a custom control. I think what i have to do is create a VS add-in that waits for me to type tokens into an .html file then it automatically creates a .cs file with members for each token.

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• How to improve my software project's speed?

  - by Blitzkr1eg

  I'm doing a school software project with my class mates in Java. We store the info on a remote db. When we start the application we pull all the information from the database and transform it into objects to use in our application (using java sql statemens). In the application we edit some of these objects and then when we exit the application we save or update information in the database using Hibernate. As you see we dont use Hibernate for pulling in information, we use it just for saving and updating. We have 2, but very similar problems. The loading of object(when we start the app) and the saving of objects(with Hibernate) in the db(when closing the app) is taking too much time. And our project its not a huge enterprise application, its a quite small app, we just manage some students, teachers, homeworks and tests. So our db is also very very small. How could we increase performance ? later edit: if we use a local database it runs very quick, it just runs slow on remote databases

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• Why isn't my leak detected by Xcode Intrumensts?

  - by Arlaharen

  I am trying to analyze some code of mine, looking for memory leaks. My problem is that some of my objects are leaking (at least as far as I can see), but the Leaks tool doesn't detect the leaks. My guess is that some iPhone OS object still holds pointers to my leaked objects. The objects I am talking about are subclasses of UIViewController that I use like this: MyController *controller = [[MyController alloc] initWithNibName:@"MyController" bundle:nil]; [self.navigationController pushViewController:controller animated:YES]; When these objects are no longer needed I do: [self.navigationController popViewControllerAnimated:YES]; Without a [controller release] call right now. Now when I look at what objects that gets created I see a lot of MyController instances that never gets destroyed. To me these are memory leaks, but to the Leaks tool they are not. Can someone here tell me if there is some way Instruments can tell me what objects are pointing to my MyController instances and thereby making them not count as memory leaks? Or better yet, tell me why these leaks are not detecetd.

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• Main purpose of this task is to calculate volumes and surface areas of three dimensional geometric shapes like, cylinders, cones.

  - by Csc_Girl_Geek

  In Java Language Design your classes as below introducing: an Interface named “GeometricShapes” an abstract class named “ThreeDShapes” two child classes of ThreeDShapes: Cylinders and Cones. One test class names “TestShapes” Get the output for volumes and surface areas of cylinders and cones along with respective values of their appropriate input variables. Try to use toString() method and array. Your classes should be designed with methods that are required for Object-Oriented programming. So Far I Have: package Assignment2; public interface GeometricShapes { public void render(); public int[] getPosition(); public void setPosition(int x, int y); } package Assignment2; public abstract class ThreeDShapes implements GeometricShapes { public int[] position; public int[] size; public ThreeDShapes() { } public int[] getPosition() { return position; } public void setPosition(int x, int y) { position[0] = x; position[1] = y; } } package Assignment2; public class Cylinders extends ThreeDShapes { public Cylinder() { } public void render() { } } I don't think this is right and I do not know how to fix it. :( Please help.

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• Remove a ReactiveCocoa signal from a control

  - by dbarros

  If I assign a signal to a property of a control: RAC(self.loginButton.enabled) = [RACSignal combineLatest:@[ self.usernameTextField.rac_textSignal, self.passwordTextField.rac_textSignal ] reduce:^(NSString* username, NSString* password) { return @(username.length > 0 && password.length > 0); }]; But then wanted to assign a different RACSignal to enabled, how can I clear any existing one before doing so? If I try and set it a second time, I get an exception like the following: 2013-10-29 16:54:50.623 myApp[3688:c07] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Signal <RACSignal: 0x975e9e0> name: +combineLatest: ( "<RACSignal: 0x975d600> name: <UITextField: 0x10f2c420> -rac_textSignal", "<RACSignal: 0x975de30> name: <UITextField: 0x10f306e0> -rac_textSignal" ) reduce: is already bound to key path "self.loginButton.enabled" on object <LoginViewController: 0x10f264e0>, adding signal <RACSignal: 0x9763500> name: +combineLatest: ( "<RACSignal: 0x97624f0> name: <UITextField: 0x10f2c420> -rac_textSignal", "<RACSignal: 0x97629e0> name: <UITextField: 0x10f306e0> -rac_textSignal" ) reduce: is undefined behavior'

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• When to use () with classes?

  - by SoulBeaver

  This is really starting to confuse the hell out of me. When do I use them, when don't I? For example I was reading a .cpp on linked lists whose class declaration was: struct CarPart { long PartNumber; char Partname[40]; double UnitPrice; CarPart *next; }; class ListOfParts { int size; public: CarPart *head; ListOfParts(); ~ListOfParts(); const int count() const; void insert( CarPart *item ); CarPart *retrieve( int pos ); }; With this code, why am I allowed to write ListOfParts *pPart = new ListOfParts(); CarPart *pCarPart = new CarPart; Declaring an instance of ListOfParts requires (), but not my CarPart? That's confusing me. When I asked a question before and people told me that such a declaration is a function that returns a ListOfParts object, but not the actual constructor. So I'm guessing this is still something different. What's happening here? PS: Am I correct to assume that the const to the right of count() means I cannot modify any values in count?

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